This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science, ICT, and Future Planning (# 2015R1A2A2A01006446).

1. Preparação de Superfície para formação de biofilme <ol><li> Corte 1 mm de espessura 304 chapas de aço inoxidável em chips (10 × 10 mm 2) com um cortador mecânico. </li><li> Executar a limpeza ultra-sónica das fichas em acetona, metanol, e água desionizada (DI) sequencialmente água durante 10 min cada. Usar um recipiente resistente a solventes, feita de substâncias tais como vidro, para remover a contaminação orgânica. </li><li> Lave as batatas fritas com água de fluxo DI para 3-5 seg. </li><li> Secam-se as batatas fritas usando o fluxo de gás N2 durante 3-5 seg. </li></ol> 2. Preparação de uma cultura bacteriana <ol><li> Tome um P. putida KT2440 (gentilmente cedido pelo Prof. Sung Kuk Lee, UNIST, Coreia do Sul) Stock armazenado em um -80 ° C congelador. </li><li> Descongelar à temperatura ambiente após 1 min, e a camada de topo da solução estoque congelada transforma a lama. Imergir uma malha na camada derretida da solução estoque. </li><li> Utilize este loop para raia as bactérias em um Luriaplaca -Bertani (LB) contendo 1,5% de agar. </li><li> Incubar a placa durante a noite a 30 ° C para crescer as colónias bacterianas. </li><li> Escolher uma única colónia da placa utilizando um loop fresco. </li><li> Inocular 10 ml de caldo de LB num tubo cónico de 50 ml, com o loop contendo a colónia bacteriana único. </li><li> Incubar o caldo num incubador com agitação durante 16 horas a 30 ° C e 160 rpm. </li></ol> 3. formação de biofilme na superfície <ol><li> Pegue cada uma das fichas preparadas com uma pinça e mergulhá-los em 70% de etanol 5 vezes por 1-2 segundos cada, para esterilizar a superfície de cada chip. Certifique-se de que os chips são realizadas com uma pinça durante o mergulho. </li><li> Mergulhe cada chip em água DI autoclavado e em caldo LB sequencialmente, 5 vezes para 1-2 segundos cada, para remover o etanol remanescente. </li><li> Coloque esses chips em placas de cultura de 6 poços com 2 chips e 5 ml de caldo LB por poço. </li><li> Dilui-se a cultura bacteriana até que a concentração no caldo LB atinge8 x 10 8 culas / mL (densidade óptica a 600 nm de comprimento de onda: ~ 0,8). </li><li> Inocular cada poço com 50 uL da cultura bacteriana diluída. </li><li> Incubar as placas a 30 ° C sem agitação durante 24 horas, para a formação de biofilmes. </li></ol> Lavagem 4. CO 2 Aerosol <ol><li> Mergulhe as batatas fritas em forma de biofilme em tampão de acetato de amónio 10 mM (voláteis) 5 vezes para remover frouxamente ligado e bactérias planctônicas. </li><li> Secar esses chips em uma cabine de segurança biológica, onde o ar flui suavemente. </li><li> Imediatamente após secagem, colocar um chip no local de carregamento, que é de 20 mm a partir do bico de CO 2 ao longo do eixo do jacto. Inclinação do eixo do jacto para um ângulo de 40 °. </li><li> Defina as pressões de estagnação de CO 2 e N 2 de gás para 5,3 MPa e 0,7 MPa, respectivamente, utilizando os reguladores de pressão de gás. </li><li> Aplicar o jacto de aerossol sobre a parte central do chip. Aerossóis brancas, incluindo o CO2 sólido deveser visível. &quot;Ligar&quot; a válvula solenóide de CO 2 durante 5 segundos e, em seguida, transformá-lo &quot;off&quot; por 3 segundos (ciclo: 8 seg) periodicamente, utilizando um interruptor controlado manualmente. Se uma purga de azoto necessita de ser usado, ligar a válvula de solenóide para um fornecimento contínuo de N 2. </li><li> Trate os chips com CO 2 aerossóis para 16, 40 e 88 segundos, com e sem purgas de azoto. Reter fichas sem tratamento como controlos negativos. </li></ol> 5. Análise para Eficiência de Remoção <ol><li> Prepare 1 mM ácido mancha de fluorescência nucleico verde (comprimento de onda de excitação / emissão: 480/500 nm) em água DI para corar células bacterianas no controle e batatas fritas tratados com aerossol. </li><li> Coloque as fichas na solução de coloração. </li><li> Incubar as batatas fritas em uma incubadora, sem luz, a 37 ° C durante 30 min. </li><li> Após a incubação, lave as batatas fritas com água de fluxo DI para remover corante fluorescente excessiva. </li><li> Seque o wi fichasth fluxo de gás de N2. </li><li> Tome fluorescência imagens microscópicas de 5 campos aleatórios de vista (321 × 240 mm 2) para cada chip usando um microscópio de epifluorescência, uma lente objetiva de 40X, e uma câmera CCD. </li><li> Obter a intensidade de fluorescência para cada imagem usando um software de processamento de imagem, tais como ImageJ. No ImageJ, use a função &quot;Background Subtrair&quot; no menu &quot;Processos&quot;, e selecione &quot;densidade integrada&quot; na janela &quot;Definir Medidas&quot; no menu &quot;Analisar&quot;. Faça o &quot;Medição&quot; no menu &quot;Analisar&quot; para obter a intensidade de fluorescência. </li><li> Calcula-se a eficiência de remoção de biofilme de acordo com a seguinte fórmula:% 100 x (I de chips de controle - I de chips tratados) / (I de chips de controle), onde I é a intensidade de fluorescência calculado. </li><li> Obter a média de eficiência na remoção e desvios-padrão. use pelopelo menos 4 chips para cada caso. </li></ol>

<ol>
	<li>Jain, A., Gupta, Y., Agrawal, R., Khare, P., Jain, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biofilms+-+A+microbial+life+perspective:+A+critical+review.">Biofilms - A microbial life perspective: A critical review.</a> Crit. Rev. Ther. Drug. 24 (5), 393-443 (2007).</li><li>Bott, T. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biofouling+control+with+ultrasound.">Biofouling control with ultrasound.</a> Heat Transfer Eng. 21 (3), 43-49 (2000).</li><li>Meyer, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Approaches+to+prevention,+removal+and+killing+of+biofilms.">Approaches to prevention, removal and killing of biofilms.</a> Int. Biodeterior. Biodegradation. 51 (4), 249-253 (2003).</li><li>Hong, S. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+electric+currents+on+bacterial+detachment+and+inactivation.">Effect of electric currents on bacterial detachment and inactivation.</a> Biotechnol. Bioeng. 100 (2), 379-386 (2008).</li><li>Nandakumar, K., Obika, H., Utsumi, A., Ooie, T., Yano, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+laser+ablation+of+laboratory+developed+biofilms+using+an+Nd:YAG+laser+of+532+nm+wavelength.">In vitro laser ablation of laboratory developed biofilms using an Nd:YAG laser of 532 nm wavelength.</a> Biotechnol. Bioeng. 86 (7), 729-736 (2004).</li><li>Gibson, H., Taylor, J. H., Hall, K. E., Holah, J. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effectiveness+of+cleaning+techniques+used+in+the+food+industry+in+terms+of+the+removal+of+bacterial+biofilms.">Effectiveness of cleaning techniques used in the food industry in terms of the removal of bacterial biofilms.</a> J. Appl. Microbiol. 87 (1), 41-48 (1999).</li><li>Kang, M. Y., Jeong, H. W., Kim, J., Lee, J. W., Jang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Removal+of+biofilms+using+carbon+dioxide+aerosols.">Removal of biofilms using carbon dioxide aerosols.</a> J. Aerosol Sci. 41 (11), 1044-1051 (2010).</li><li>Cha, M., Hong, S., Kang, M. Y., Lee, J. W., Jang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gas-phase+removal+of+biofilms+from+various+surfaces+using+carbon+dioxide+aerosols.">Gas-phase removal of biofilms from various surfaces using carbon dioxide aerosols.</a> Biofouling. 28 (7), 681-686 (2012).</li><li>Dwidar, M., Hong, S., Cha, M., Jang, J., Mitchell, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Combined+application+of+bacterial+predation+and+carbon+dioxide+aerosols+to+effectively+remove+biofilms.">Combined application of bacterial predation and carbon dioxide aerosols to effectively remove biofilms.</a> Biofouling. 28 (7), 671-680 (2012).</li><li>Cha, M., Hong, S., Lee, S. Y., Jang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Removal+of+different-age+biofilms+using+carbon+dioxide+aerosols.">Removal of different-age biofilms using carbon dioxide aerosols.</a> Biotechnol. Bioprocess Eng. 19 (3), 503-509 (2014).</li><li>Singh, R., Monnappa, A. K., Hong, S., Mitchell, R. J., Jang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+Carbon+Dioxide+Aerosols+on+the+Viability+of+Escherichia+coli+during+Biofilm+Dispersal.">Effects of Carbon Dioxide Aerosols on the Viability of Escherichia coli during Biofilm Dispersal.</a> Sci. Rep. 5, 13766 (2015).</li><li>Sherman, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Carbon+Dioxide+Snow+Cleaning.">Carbon Dioxide Snow Cleaning.</a> Particul. Sci.Technol. 25 (1), 37-57 (2007).</li></ol>

The authors declare that they have no competing financial interests.

Previously, we conducted optimization studies on CO2 gas pressure, jet angle, and distance to the solid surface in CO2 aerosol cleaning7. Unlike our previous studies, in the present study, a nitrogen purge was not included in the aerosol (Figure 1). Moreover, 304 stainless steel was used in this protocol, since it is one of the most common stainless steels and is widely used in the food industry. The polished surface is beneficial for fluorescence analysis because of a un...

Biofilms are complex bacterial community structures in which bacterial cells are embedded within self-produced matrices of extracellular polymeric substances, held together, and protected from the external environment. Biofilms can present a public health risk and cause economic losses because they can form on various surfaces, including medical implant materials and devices, food processing equipment, and heat exchangers. In fact, biofilms have been found to be associated with 65% of all bacterial infectious diseases in humans, according to the Centers for Disease Control and Prevention1.
Autoclaves and disinfectants such as chlorine have generally been used for the inactivation of biofilms. However, the use of an autoclave is limited for surfaces that can neither withstand high temperature steam nor be placed into the autoclave. Disinfectants are not suitable for surfaces sensitive to chemical treatment or prone to collecting toxic oxidation products2. In addition, the biofilm should not only be inactivated, but also removed in order to prevent the attachment of new cells onto the surface, thereby forming a new biofilm3. However, it is difficult to remove biofilms using methods based on viscous fluid shear because the flow velocity near the surface is almost zero and the shear force usually cannot overcome the adhesive forces of micron- and submicron-sized substances. Moreover, the biofilm matrix is known to act as a physical and chemical barrier1.
Many physical and mechanical techniques have been developed to remove biofilms from surfaces, including ultrasonic vibration1, electric currents4, laser irradiation5, and high-pressure water sprays6. Each technique has its own pros and cons. Ultrasonic vibration and electric current can be used to control biofilm formation; however, they require a particular configuration and conductive surfaces, respectively, requiring additional shear stress1, 4. Laser irradiation can be applied to a limited area and to hard surfaces; however, some live and dead cells remain on the surface5. High-pressure water sprays effectively remove biofilms; however, their high momentum can cause damage to soft substrates6.
Biofilm removal using CO2 aerosols has been previously proposed. It has shown promising results, with high removal efficiencies within a short time7-11. CO2 aerosols are generated by adiabatic expansion of a high-pressure CO2 gas through a nozzle, and they are applied to the surfaces contaminated with a biofilm. This cleaning technique utilizes the momentum transfer of solid CO2 particles and the solvent action of the melted CO2 liquids, followed by the aerodynamic shear force of the CO2 gas12. Compared with high-pressure N2 gas jets, CO2 aerosol jets at the same stagnation pressure are much more effective in removing E. coli biofilms7. Moreover, although the momentum of the solid CO2 that is delivered to the bacteria is considerably high, the momentum of the total aerosol jet applied to the solid surface is substantially lower than that of water jets. Therefore, damage-free cleaning is possible using this CO2 aerosol technique.
In this protocol, periodic jets of CO2 aerosols without nitrogen purges were used to remove Pseudomonas putida biofilms from a polished stainless steel surface. In fact, nitrogen purges have been used in many CO2 aerosol studies to increase the removal efficiency by reducing the moisture condensation generated during the cleaning, even though heating with a hot plate or infrared lamps and employing dry boxes have also been adopted12. The surface biofilm formation and the optimized cleaning procedures are described below. The removal efficiency was evaluated by measuring the fluorescence intensity of the biofilm on the surface.

<table border="0" cellpadding="0" cellspacing="0" width="573">
	<tbody>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">304 stainless steel</td>
			<td style="width:71px;">Steelni 
			(South Korea)</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">Polished and diced ones</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Ultrasonic cleaner</td>
			<td style="width:71px;">Branson 
			(USA)</td>
			<td style="width:119px;">5510E-DTH</td>
			<td></td>
		</tr>
		<tr height="105">
			<td height="105" style="height:105px;width:216px;">Luria-Bertani (LB)</td>
			<td style="width:71px;">Becton, Dickinson and Company 
			(USA)</td>
			<td style="width:119px;">244620</td>
			<td>500 g</td>
		</tr>
		<tr height="105">
			<td height="105" style="height:105px;width:216px;">Agar</td>
			<td style="width:71px;">Becton, Dickinson and Company 
			(USA)</td>
			<td style="width:119px;">214010</td>
			<td>500 g</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">6-well culture plate</td>
			<td style="width:71px;">SPL Life Sciences 
			(South Korea)</td>
			<td style="width:119px;">32006</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Ammonium acetate buffer</td>
			<td style="width:71px;">Sigma-Aldrich 
			(USA)</td>
			<td style="width:119px;">667404</td>
			<td>10 mM</td>
		</tr>
		<tr height="105">
			<td height="105" style="height:105px;width:216px;">Dual gas unit</td>
			<td style="width:71px;">Applied Surface Technologies 
			(USA)</td>
			<td style="width:119px;">K6-10DG</td>
			<td style="width:167px;">One nozzle for CO2 gas 
			&#38; 8 nozzles for N2 gas</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">SYTO9</td>
			<td style="width:71px;">Thermo Fissher Scientific 
			(USA)</td>
			<td style="width:119px;">Invitrogen</td>
			<td style="width:167px;">Excitaion: 480 nm 
			Emission: 500 nm</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Epifluorescence microscope&#160;</td>
			<td style="width:71px;">Nikon (Japan)</td>
			<td style="width:119px;">Eclipse 80i</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">40&#215; objective lens</td>
			<td style="width:71px;">Nikon 
			(Japan)</td>
			<td style="width:119px;">Plan Fluor</td>
			<td>NA: 0.75</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">CCD camera&#160;</td>
			<td style="width:71px;">Photometrics 
			(USA)</td>
			<td style="width:119px;">Cool SNAP HQ2</td>
			<td>Monochrome</td>
		</tr>
	</tbody>
</table>

biofilm removal using carbon dioxide aerosols without nitrogen purge

Biofilms can cause serious concerns in many applications. Not only can they cause economic losses, but they can also present a public health hazard. Therefore, it is highly desirable to remove biofilms from surfaces. Many studies on CO2 aerosol cleaning have employed nitrogen purges to increase biofilm removal efficiency by reducing the moisture condensation generated during the cleaning. However, in this study, periodic jets of CO2 aerosols without nitrogen purges were used to remove Pseudomonas putida biofilms from polished stainless steel surfaces. CO2 aerosols are mixtures of solid and gaseous CO2 and are generated when high-pressure CO2 gas is adiabatically expanded through a nozzle. These high-speed aerosols were applied to a biofilm that had been grown for 24 hr. The removal efficiency ranged from 90.36% to 98.29% and was evaluated by measuring the fluorescence intensity of the biofilm as the treatment time was varied from 16 sec to 88 sec. We also performed experiments to compare the removal efficiencies with and without nitrogen purges; the measured biofilm removal efficiencies were not significantly different from each other (t-test, p &gt; 0.55). Therefore, this technique can be used to clean various bio-contaminated surfaces within one minute.

CO 2 aerossóis foram usadas para remover o P. putida biofilmes de superfícies SUS304 (Figura 1). A maior parte das superfícies foram cobertas com o biofilme, após 24 h de crescimento. A maior parte do biofilme foi removido utilizando o CO 2 aerossóis (Figura 2). Como esperado, a Figura 3 mostra um aumento na eficiência de remoção do biofilme como o CO 2 tempo de tratamento de aerossol aumentou. Para o tempo de tratamento...

Watch this Scientific Journal Video about Biofilm Removal Using Carbon Dioxide Aerosols without Nitrogen Purge at JoVE.com

Biofilm Removal Using Carbon Dioxide Aerosols without Nitrogen Purge

Biofilms on surfaces can be effectively and rapidly removed by using a periodic jet of carbon dioxide aerosols without a nitrogen purge.

A remoção do biofilme uso de aerossóis de dióxido de carbono sem a purga de azoto

Biofilms can cause serious concerns in many applications. Not only can they cause economic losses, but they can also present a public health hazard. ...

biofilm-removal-using-carbon-dioxide-aerosols-without-nitrogen-purge

Research

Education

JoVE Core

JoVE Journal

Physics

Environment

Unit 1

The First Law of Thermodynamics

SCIENTISTS IN ACTION

6.3K visualizações.  Ulsan National Institute of Science and Technology (UNIST). Biofilms on surfaces can be effectively and rapidly removed by using a periodic jet of carbon dioxide aerosols without a nitrogen purge.

Vídeo: Biofilm Removal Using Carbon Dioxide Aerosols without Nitrogen Purge

The Use of an Automated System (GreenFeed) to Monitor Enteric Methane and Carbon Dioxide Emissions from Ruminant Animals

Ruminant animals (domesticated or wild) emit methane (CH4) through enteric fermentation in their digestive tract and from decomposition of manure during storage. These processes are the major sources of greenhouse gas (GHG) emissions from animal production systems. Techniques for measuring enteric CH4 vary from direct measurements (respiration chambers, which are highly accurate, but with limited applicability) to various indirect methods (sniffers, laser technology, which are practical, but with variable accuracy). The sulfur hexafluoride (SF6)&#160;tracer gas method is commonly used to measure enteric CH4 production by animal scientists and more recently, application of an Automated Head-Chamber System (AHCS) (GreenFeed, C-Lock, Inc., Rapid City, SD), which is the focus of this experiment, has been growing. AHCS is an automated system to monitor CH4 and carbon dioxide (CO2) mass fluxes from the breath of ruminant animals. In a typical AHCS operation, small quantities of baiting feed are dispensed to individual animals to lure them to AHCS multiple times daily. As the animal visits AHCS, a fan system pulls air past the animal&#8217;s muzzle into an intake manifold, and through an air collection pipe where continuous airflow rates are measured. A sub-sample of air is pumped out of the pipe into non-dispersive infra-red sensors for continuous measurement of CH4 and CO2 concentrations. Field comparisons of AHCS to respiration chambers or SF6 have demonstrated that AHCS produces repeatable and accurate CH4 emission results, provided that animal visits to AHCS are sufficient so emission estimates are representative of the diurnal rhythm of rumen gas production. Here, we demonstrate the use of AHCS to measure CO2 and CH4 fluxes from dairy cows given a control diet or a diet supplemented with technical-grade cashew nut shell liquid.

The Use of an Automated System GreenFeed to Monitor Enteric Methane and Carbon Dioxide Emissions from Ruminant Animals

Accuracy and precision of the techniques used to measure methane emissions from ruminant animals are critically important for the success of greenhouse gas mitigation efforts. This manuscript describes the principles and operation of an automated system to monitor methane and carbon dioxide mass fluxes from the breath of ruminant animals.

O uso de um sistema automatizado (GreenFeed) para monitorar entérica de metano e dióxido de carbono As emissões dos ruminantes

Ruminant animals (domesticated or wild) emit methane (CH4) through enteric fermentation in their digestive tract and from decomposition of manure during ...

Ambiente

Measuring Carbon-based Contaminant Mineralization Using Combined CO2 Flux and Radiocarbon Analyses

A method is described which uses the absence of radiocarbon in industrial chemicals and fuels made from petroleum feedstocks which frequently contaminate the environment. This radiocarbon signal &#8212; or rather the absence of signal &#8212; is evenly distributed throughout a contaminant source pool (unlike an added tracer) and is not impacted by biological, chemical or physical processes (e.g., the 14C radioactive decay rate is immutable). If the fossil-derived contaminant is fully degraded to CO2, a harmless end-product, that CO2 will contain no radiocarbon. CO2 derived from natural organic matter (NOM) degradation will reflect the NOM radiocarbon content (usually &#60;30,000 years old). Given a known radiocarbon content for NOM (a site background), a two end-member mixing model can be used to determine the CO2 derived from a fossil source in a given soil gas or groundwater sample. Coupling the percent CO2 derived from the contaminant with the CO2 respiration rate provides an estimate for the total amount of contaminant degraded per unit time. Finally, determining a zone of influence (ZOI) representing the volume from which site CO2 is collected allows determining the contaminant degradation per unit time and volume. Along with estimates for total contaminant mass, this can ultimately be used to calculate time-to-remediate or otherwise used by site managers for decision-making.

Measuring Carbon-based Contaminant Mineralization Using Combined CO2 Flux and Radiocarbon Analyses

A protocol is described wherein CO2 mineralized from organic contaminant (derived from petroleum feedstocks) biodegradation is trapped, quantified, and analyzed for 14C content. A model is developed to determine CO2 capture zone's spatial extent. Spatial and temporal measurements allow integrating contaminant mineralization rates for predicting remediation extent and time.

Medindo-carbono com base Contaminant Mineralização Usando Combinada CO<sub&gt; 2</sub&gt; fluxo e de radiocarbono Análises

A method is described which uses the absence of radiocarbon in industrial chemicals and fuels made from petroleum feedstocks which frequently contaminate ...

Assessment of Labile Organic Carbon in Soil Using Sequential Fumigation Incubation Procedures

Management practices and environmental changes can alter soil nutrient and carbon cycling. Soil labile organic carbon, a readily decomposable C pool, is highly sensitive to disturbance. It is also the primary substrate for soil microorganisms, which is fundamental to nutrient cycling. Due to these attributes, labile organic carbon (LOC) has been identified as an indicator parameter for soil health. Quantifying the turnover rate of LOC also aids in understanding changes in soil nutrient cycling processes. A sequential fumigation incubation method has been developed to estimate soil LOC and potential C turnover rate. The method requires fumigating soil samples and quantifying CO2-C respired during a 10 day incubation period over a series of fumigation-incubation cycles. Labile organic C and potential C turnover rate are then extrapolated from accumulated CO2 with a negative exponential model. Procedures for conducting this method are described.

Labile organic carbon (LOC) and the potential carbon turnover rate are sensitive indicators of changes in soil nutrient cycling processes. Details are provided for a method based on fumigating and incubating soil in a series of cycles and using the CO2 accumulated during the incubation periods to estimate these parameters.

Avaliação da lábil carbono orgânico no solo usando procedimentos seqüenciais Fumigação de incubação

Management practices and environmental changes can alter soil nutrient and carbon cycling. Soil labile organic carbon, a readily decomposable C pool, is ...

Automated, High-resolution Mobile Collection System for the Nitrogen Isotopic Analysis of NOx

Nitrogen oxides (NOx = NO + NO2) are a family of atmospheric trace gases that have great impact on the environment. NOx concentrations directly influence the oxidizing capacity of the atmosphere through interactions with ozone and hydroxyl radicals. The main sink of NOx is the formation and deposition of nitric acid, a component of acid rain and a bioavailable nutrient. NOx is emitted from a mixture of natural and anthropogenic sources, which vary in space and time. The collocation of multiple sources and the short lifetime of NOx make it challenging to quantitatively constrain the influence of different emission sources and their impacts on the environment. Nitrogen isotopes of NOx have been suggested to vary amongst different sources, representing a potentially powerful tool to understand the sources and transport of NOx. However, previous methods of collecting atmospheric NOx integrate over long (week to month) time spans and are not validated for the efficient collection of NOx in relevant, diverse field conditions. We report on a new, highly efficient field-based system that collects atmospheric NOx for isotope analysis at a time resolution between 30 min and 2 hr. This method collects gaseous NOx in solution as nitrate with 100% efficiency under a variety of conditions. Protocols are presented for collecting air in urban settings under both stationary and mobile conditions. We detail the advantages and limitations of the method and demonstrate its application in the field. Data from several deployments are shown to 1) evaluate field-based collection efficiency by comparisons with in situ NOx concentration measurements, 2) test the stability of stored solutions before processing, 3) quantify in situ reproducibility in a variety of urban settings, and 4) demonstrate the range of N isotopes of NOx detected in ambient urban air and on heavily traveled roadways.

Automated, High-resolution Mobile Collection System for the Nitrogen Isotopic Analysis of NOx

Previous work suggests that the nitrogen isotopic composition of atmospheric nitrogen oxides might distinguish the influence of different sources in the environment. We report on an automated, mobile, field-based method for the high collection efficiency of atmospheric NOx for N isotopic analysis at an hourly time resolution.

Automatizado, de alta resolução Sistema de Coleta Móvel para a análise de azoto isotópica de NO<sub&gt; x</sub

Nitrogen oxides (NOx = NO + NO2) are a family of atmospheric trace gases that have great impact on the environment. NOx concentrations directly influence ...

Functionalization and Dispersion of Carbon Nanomaterials Using an Environmentally Friendly Ultrasonicated Ozonolysis Process

Functionalization of carbon nanomaterials is often a critical step that facilitates their integration into larger material systems and devices. In the as-received form, carbon nanomaterials, such as carbon nanotubes (CNTs) or graphene nanoplatelets (GNPs), may contain large agglomerates. Both agglomerates and impurities will diminish the benefits of the unique electrical and mechanical properties offered when CNTs or GNPs are incorporated into polymers or composite material systems. Whilst a variety of methods exist to functionalize carbon nanomaterials and to create stable dispersions, many the processes use harsh chemicals, organic solvents, or surfactants, which are environmentally unfriendly and may increase the processing burden when isolating the nanomaterials for subsequent use. The current research details the use of an alternative, environmentally friendly technique for functionalizing CNTs and GNPs. It produces stable, aqueous dispersions free of harmful chemicals. Both CNTs and GNPs can be added to water at concentrations up to 5 g/L and can be recirculated through a high-powered ultrasonic cell. The simultaneous injection of ozone into the cell progressively oxidizes the carbon nanomaterials, and the combined ultrasonication breaks down agglomerates and immediately exposes fresh material for functionalization. The prepared dispersions are ideally suited for the deposition of thin films onto solid substrates using electrophoretic deposition (EPD). CNTs and GNPs from the aqueous dispersions can be readily used to coat carbon- and glass-reinforcing fibers using EPD for the preparation of hierarchical composite materials.

Here, a novel method for the functionalization and stable dispersion of carbon nanomaterials in aqueous environments is described. Ozone is injected directly into an aqueous dispersion of carbon nanomaterial that is continuously recirculated through a high-powered ultrasonic cell.

Funcionalidade e Dispersão de Nanomateriais de Carbono Usando um Processo de Ozonólise Ultrasonicada Ambientalmente Amigável

Functionalization of carbon nanomaterials is often a critical step that facilitates their integration into larger material systems and devices. In the ...

Extraction and Characterization of Surfactants from Atmospheric Aerosols

Surface-active compounds, or surfactants, present in atmospheric aerosols are expected to play important roles in the formation of liquid water clouds in the Earth&#39;s atmosphere, a central process in meteorology, hydrology, and for the climate system. But because specific extraction and characterization of these compounds have been lacking for decades, very little is known on their identity, properties, mode of action and origins, thus preventing the full understanding of cloud formation and its potential links with the Earth&#39;s ecosystems.
In this paper we present recently developed methods for 1) the targeted extraction of all the surfactants from atmospheric aerosol samples and for the determination of 2) their absolute concentrations in the aerosol phase and 3) their static surface tension curves in water, including their Critical Micelle Concentration (CMC). These methods have been validated with 9 references surfactants, including anionic, cationic and non-ionic ones. Examples of results are presented for surfactants found in fine aerosol particles (diameter &#60;1 &#956;m) collected at a coastal site in Croatia and suggestions for future improvements and other characterizations than those presented are discussed.

Methods are presented for the targeted extraction of surfactants present in atmospheric aerosols and the determination of their absolute concentrations and surface tension curves in water, including their Critical Micelle Concentration (CMC).

Extração e caracterização de surfactantes de aerossóis atmosféricos

Surface-active compounds, or surfactants, present in atmospheric aerosols are expected to play important roles in the formation of liquid water clouds in ...

Measurement of the Rheology of Crude Oil in Equilibrium with CO2 at Reservoir Conditions

A rheometer system to measure the rheology of crude oil in equilibrium with carbon dioxide (CO2) at high temperatures and pressures is described. The system comprises a high-pressure rheometer which is connected to a circulation loop. The rheometer has a rotational flow-through measurement cell with two alternative geometries: coaxial cylinder and double gap. The circulation loop contains a mixer, to bring the crude oil sample into equilibrium with CO2, and a gear pump that transports the mixture from the mixer to the rheometer and recycles it back to the mixer. The CO2 and crude oil are brought to equilibrium by stirring and circulation and the rheology of the saturated mixture is measured by the rheometer. The system is used to measure the rheological properties of Zuata crude oil (and its toluene dilution) in equilibrium with CO2 at elevated pressures up to 220 bar and a temperature of 50 &#176;C. The results show that CO2 addition changes the oil rheology significantly, initially reducing the viscosity as the CO2 pressure is increased and then increasing the viscosity above a threshold pressure. The non-Newtonian response of the crude is also seen to change with the addition of CO2.

Measurement of the Rheology of Crude Oil in Equilibrium with CO2 at Reservoir Conditions

A method for measuring the rheology of crude oil in equilibrium with carbon dioxide at reservoir conditions is presented.

Medição da reologia do petróleo bruto em equilíbrio com CO<sub&gt; 2</sub&gt; Nas condições do reservatório

A rheometer system to measure the rheology of crude oil in equilibrium with carbon dioxide (CO2) at high temperatures and pressures is described. The ...

Assessing the Particulate Matter Removal Abilities of Tree Leaves

Based on the conventional cleaning methods (water cleaning (WC) + brush cleaning (BC)), this study evaluated the influence of ultrasonic cleaning (UC) on collecting various sized particulate matter (PM) retained on leaf surfaces. We further characterized the retention efficiency of leaves to various sized PM, which will help to assess the abilities of urban trees to remove PM from ambient air quantitatively. 
Taking three broadleaf tree species (Ginkgo biloba, Sophora japonica, and Salix babylonica) and two needleleaf tree species (Pinus tabuliformis and Sabina chinensis) as the research objects, leaf samples were collected 4 days (short PM retention period) and 14 days (long PM retention period) after the latest rainfall. PM retained on the leaf surfaces was collected by means of WC, BC, and UC in sequence. Then, retention efficiencies of leaves (AEleaf) to three types of the various sized PM, including easily removable PM (ERP), difficult-to-remove PM (DRP), and totally removable PM (TRP), were calculated. Only around 23%-45% of the total PM retained on leaves could be cleaned off and collected by WC. When the leaves were cleaned through WC+BC, the underestimation of the PM retention capacity of different tree species was in the range of 29%-46% for various sized PM. Almost all PM retained on leaves could be removed if UC was supplemented to WC+BC. 
In conclusion, if the UC was complemented after the conventional cleaning methods, more PM on leaf surfaces could be eluted and collected. The procedure developed in this study can be used for assessing the PM removal abilities of different tree species.

The ultrasonic cleaning method was applied to elute the particulate matter (PM) retained on leaf surfaces after PM was eluted by the conventional cleaning methods (water cleaning only or water cleaning plus brush cleaning). The methodology can help to improve the estimation accuracy for PM retention capacity of leaves.

Avaliar as habilidades de remoção de partículas de árvore folhas

Based on the conventional cleaning methods (water cleaning (WC) + brush cleaning (BC)), this study evaluated the influence of ultrasonic cleaning (UC) on ...

Preparation of Biomass-based Mesoporous Carbon with Higher Nitrogen-/Oxygen-chelating Adsorption for Cu(II) Through Microwave Pre-Pyrolysis

An environment-friendly technique for synthesizing biomass-based mesoporous activated carbon with high nitrogen-/oxygen-chelating adsorption for Cu(II) is proposed. Bagasse impregnated with phosphoric acid is utilized as the precursor. To pyrolyze the precursor, two separate heating modes are used: microwave pyrolysis and conventional electric-heating pyrolysis. The resulting bagasse-derived carbon samples are modified with nitrification and reduction modification. Nitrogen (N)/oxygen (O) functional groups are simultaneously introduced to the surface of activated carbon, enhancing its adsorption of Cu(II) by complexing and ion-exchange. Characterization and copper adsorption experiments are performed to investigate the physicochemical properties of four prepared carbon samples and determine which heating method favors the subsequent modification for doping of N/O functional groups. In this technique, based on analyzing data of nitrogen adsorption, Fourier transform infrared spectroscopy, and batch adsorption experiments, it is proven that microwave-pyrolyzed carbon has more defect sites and, therefore, time-saving effective microwave pyrolysis contributes more N/O species to the carbon, although it leads to a lower specific surface area. This technique offers a promising route to synthesis adsorbents with higher nitrogen and oxygen content and a higher adsorption capacity of heavy-metal ions in wastewater remediation applications.

Preparation of Biomass-based Mesoporous Carbon with Higher Nitrogen-/Oxygen-chelating Adsorption for CuII Through Microwave Pre-Pyrolysis

Here, we present a protocol to synthesize nitrogen/oxygen dual-doped mesoporous carbon from biomass by chemical activation in different pyrolysis modes followed by modification. We demonstrate that the microwave pyrolysis benefits the subsequent modification process to simultaneously introduce more nitrogen and oxygen functional groups on the carbon.

Preparação da biomassa de carbono de mesoporos com nitrogênio superior-/ oxigênio-quelantes de adsorção para Cu(II) através de pre-pirólise microondas

An environment-friendly technique for synthesizing biomass-based mesoporous activated carbon with high nitrogen-/oxygen-chelating adsorption for Cu(II) is ...

Measurement of Aerosols Optical Thickness of the Atmosphere using the GLOBE Handheld Sun Photometer

Here, we describe the measurement of aerosol optical thickness using the GLOBE handheld sun photometer. Aerosol optical thickness (AOT) was measured at Xavier University of Louisiana (XULA, 29.96&#176; N, 90.11&#176; W and 3 m above sea level). The measurements were done at two different wavelengths, 505 nm and 625 nm. AOT measurements were done 6 times a day (7 AM, 9 AM, 11 AM, solar noon, 3 PM and 5 PM). The data shown in this paper are the monthly average AOT values taken at solar noon. During each measurement time; at least five values of the sunlight voltage V and the dark voltage Vdark are taken for each channel. The mean for these five measurements is taken as the average for that measurement time. Other meteorological data such as temperature, surface pressure, rainfall and relative humidity are also measured at the same time. The whole protocol is completed within a time span of 10&#8211;15 min. The measured AOT values at 505 nm and 625 nm are then used to extrapolate the AOT values for wavelengths 667 nm, 551 nm, 532 nm and 490 nm. The measured and extrapolated AOT values were then compared with values from the nearest AERONET station at Wave CIS site 6 (AERONET, 28.87&#176; N, 90.48&#176; W and 33 m above sea level), which is about 96 km south of XULA. In this study we tracked the annual and daily variations of AOT for a 12 month period from September 2017 to August 2018. We also compared AOT data from two independently calibrated GLOBE handheld sun photometers at the XULA site. The data show that the two instruments are in excellent agreement.

The goal of the methods presented here is to measure aerosol optical thickness of the atmosphere. The sun photometer is pointed at the sun and the largest voltage reading obtained on an in-built digital voltmeter is recorded. Atmospheric measurements such as barometric pressure and relative humidity are also performed.

Medição de aerossóis de espessura óptica da atmosfera usando o GLOBE portátil Sun Photometer

Here, we describe the measurement of aerosol optical thickness using the GLOBE handheld sun photometer. Aerosol optical thickness (AOT) was measured at ...